Camille L. Grasso

L'individu se nourrit d’un ensemble de concepts dont il n’a pourtant aucune expérience sensorielle et motrice. Cette capacité à transcender le monde physique pour construire un univers de représentations abstraites, comme celle de temps, est considérée comme l’une des plus sophistiquées de la cognition humaine. Si l’implication des processus sensorimoteurs dans le traitement des mots concrets est aujourd’hui établie, leur rôle dans le traitement des mots abstraits est au cœur d’un vif débat. À partir de propositions théoriques comme celles de la réutilisation neuronale et de l’apprentissage par corrélation, nous proposons une piste explicative de l’ancrage des concepts abstraits temporels. Dans une série de cinq études, nous avons mis en évidence le rôle du mouvement dans l’émergence d’effets de congruence spatio-temporelle lors du traitement de mots liés au temps. Plusieurs propositions théoriques peuvent êtes faites à la lumière de nos résultats. La première est que le concept de temps pourrait s’ancrer directement dans l’expérience temporelle qui accompagne le mouvement. En ce sens, les chevauchements entre temps et espace n’impliqueraient pas que le temps soit intrinsèquement de nature spatiale, mais que temps et espace soient confondus parce que vécus ensemble via le mouvement. La deuxième est que les mécanismes qui sous-tendent la représentation et le traitement des concepts temporels pourraient réutiliser ceux de la planification motrice et de la cognition spatiale. La troisième est que l’action répétée de lecture et d’écriture pourrait constituer l’expérience sensorimotrice de premier ordre qui définit le cadre d’ancrage de temps, et lie ensemble espace et temps.

Is there a geometry of time in the human mind? A canonical measure of time in psychology is duration, a time interval quantifiable as a magnitude. Durations have been proposed to be arranged along a mental timeline: a unidimensional, linear, and spatialised representation of time. Here, we asked whether such a mental timeline is sufficient to account for the experience of duration. To address this, we tested the same participants in two experiments: a behavioural similarity judgment task, in which participants rated the similarity of duration pairs, and an electroencephalography (EEG) experiment in which they detected oddball durations in a sequence. Behavioural and EEG data were used to construct representational dissimilarity matrices, whose geometry was compared against theoretical models of duration organisation. Our results reveal that most variance in behavioural similarity judgements is explained by three latent dimensions, interpretable as: magnitude (monotonic ordering of durations), contextual encoding (distance to the geometric mean of the duration set), and a periodic component. These three dimensions are jointly consistent with a latent generalised helical model, which provided excellent fit to the behavioural data. Individual helical model parameters further correlated with endogenous neural oscillations measured during rest, suggesting that an individual’s duration space is partially constrained by intrinsic dynamics. The neural geometry was also found to be dynamic, unfolding in two successive stages: a strong logarithmic encoding of durations peaking around 150 ms after duration offset, followed by a spring-like geometry starting around 300 ms after offset. Together, these findings describe multidimensional psychological and neural geometries of duration space, and characterise their relationship.

How does the structure of events influence the when and the where of experience in comparison to the what? We developed a novel virtual reality (VR) environment to understand how the quantity of information within nested structures influence participants' memory for events. Participants moved through a series of virtual rooms (events) where images (items) appeared in randomised locations on a 3 by 3 grid located on a wall. Participants were asked to remember the what (old/new), when (timeline location), and where (grid location), of the images they experienced. Two types of nested events were tested (6 rooms, each containing 4 images; 3 rooms, each containing 8 images) without a difference in the number of seconds of presentation. We found a strong temporal compression effect at nested levels in which participants remembered early items and events happening later, and later items and events happening earlier, than the original experience. Crucially, presenting four-item events resulted in a greater compression rate than eight-item events. We also found greater temporal distances between pairs of items occurring within eight-item events than pairs of items which occurred on either side of a boundary. Memory for when depends on the compression of information within events.

How do people grasp the abstract concept of time? It has been argued that abstract concepts, such as future and past, are grounded in sensorimotor experience. When responses to words that refer to the past or the future are either spatially compatible or incompatible with a left-to-right timeline, a space-time congruency effect is observed. In the present study, we investigated whether reading expertise determines the strength of the space-time congruency effect, which would suggest that learning to read and write drives the effect. Using a temporal categorization task, we compared two types of space-time congruency effects, one where spatial incongruency was generated by the location of the stimuli on the screen and one where it was generated by the location of the responses on the keyboard. While the first type of incongruency was visuo-spatial only, the second involved the motor system. Results showed stronger space-time congruency effects for the second type of incongruency (i.e., when the motor system was involved) than for the first type (visuo-spatial). Crucially, reading expertise, as measured by a standardized reading test, predicted the size of the space-time congruency effects. Altogether, these results reinforce the claim that the spatial representation of time is partially mediated by the motor system and partially grounded in spatially-directed movement, such as reading or writing.

In Western cultures where people read and write from left to right, time is represented along a spatial continuum that goes from left to right (past to future), known as the mental timeline (MTL). In language, this MTL was supported by space–time congruency effects: People are faster to make lexical decisions to words conveying past or future information when left/right manual responses are compatible with the MTL. Alternatively, in cultures where people read from right to left, space–time congruency effects go in the opposite direction. Such cross-cultural differences suggest that repeated writing and reading dynamic movements are critically involved in the spatial representation of time. In most experiments on the space–time congruency effect, participants use their hand for responding, an effector that is associated to the directionality of writing. To investigate the role of the directionality of reading in the space–time congruency effect, we asked participants to make lateralized eye movements (left or right saccades) to indicate whether stimuli were real words or not (lexical decision). Eye movement responses were slower and higher in amplitude for responses incompatible with the direction of the MTL. These results reinforce the claim that repeated directional reading and writing movements promote the embodiment of time-related words.

Humans are equipped with a set of concepts of which they have no perceptive or motor experience. This capacity to transcend the physical world to build a universe of abstract representations, such as astrophysics or time, is one of the most sophisticated of human cognition. If the involvement of sensorimotor processes in the processing of concrete words is now established, their role in the representation and the processing of abstract concepts is at the heart of a lively debate. Based on a detailed review of data from the literature, and theoretical proposals such as neural reuse and correlational learning, we examined the way in which temporal abstract concepts could be grounded. In a series of five experiments, we investigated the role of movement in the emergence of space-time congruency effects during the visual processing of words conveying temporal information. Overall, our results suggest that movement plays a key role for the grounding (and the processing) of the temporal content of these words. Considering our results, several theoretical propositions (not exclusive) can be made. First, the abstract concept of time could be directly grounded in the temporal experience that accompanies the execution of the movement. In this sense, the overlaps between time and space would not imply that time is intrinsically spatial in nature, but that time and space are generally confused because they are experienced together through movement. Second, the mechanisms underlying the representation and processing of temporal concepts could reuse those of motor planning and spatial cognition. Third, the repeated action of reading and writing could constitute the sensorimotor experience that links space and time together.

How do people grasp the abstract concept of time? It has been argued that abstract concepts, such as future and past, are grounded in sensorimotor experience. When responses to words that refer to the past or the future are either spatially compatible or incompatible with a left-to-right timeline, a space-time congruency effect is observed. In the present study, we investigated whether reading expertise determines the strength of the space-time congruency effect, which would suggest that learning to read and write drives the effect. Using a temporal categorization task, we compared two types of space-time congruency effects, one where spatial incongruency was generated by the location of the stimuli on the screen and one where it was generated by the location of the responses on the keyboard. While the first type of incongruency was visuo-spatial only, the second involved the motor system. Results showed stronger space-time congruency effects for the second type of incongruency (i.e., when the motor system was involved) than for the first type (visuo-spatial). Crucially, reading expertise, as measured by a standardized reading test, predicted the size of the space-time congruency effects. Altogether, these results reinforce the claim that the spatial representation of time is partially mediated by the motor system and partially grounded in spatially-directed movement, such as reading or writing.

The processing of time activates a spatial left-to-right mental timeline, where past events are "located" to the left and future events to the right. If past and future words activate this mental timeline, then the processing of such words should interfere with hand movements that go in the opposite direction. To test this hypothesis, we conducted 3 visual lexical decision tasks with conjugated (past/future) verbs and pseudoverbs. In Experiment 1, participants moved a pen to the right or left of a trackpad to indicate whether a visual stimulus was a real word or not. Grammatical time and hand movements for yes responses went in the same direction in the congruent condition (e.g., past tense/leftward movement) but in opposite directions in the incongruent condition. Analyses showed that space-time incongruency significantly increased reaction times. In Experiment 2, we investigated the role of movement in this effect. Participants performed the same task by responding with a trackpad or a mouse, both of which required lateral movement through space, or a static keypress. We again obtained the space-time congruency effect, but only when the decision required movement through space. In Experiments 1 and 2, stimuli were preceded by a temporal prime. In Experiment 3, participants performed the same task without any prime. Results replicated the congruency effect, demonstrating that it does not depend upon temporal word priming. Altogether, results suggest automatic activation of a left-right mental timeline during word recognition, reinforcing the claim that the concept of Time is grounded in movement through space. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

In Western cultures where people read and write from left-to-right, time is represented along a spatial continuum that goes from left to right (past to future), known as the mental timeline (MTL). In language, this MTL was supported by space-time congruency effects: people are faster to make lexical decisions to words conveying past or future information when left/right manual responses are compatible with the MTL. Alternatively, in cultures where people read from right-to-left, space-time congruency effects go in the opposite direction. Such cross-cultural differences suggest that repeated writing and reading dynamic movements are critically involved in the spatial representation of time. In most experiments on the space-time congruency effect, participants use their hand for responding, an effector that is associated to the directionality of writing. To investigate the role of the directionality of reading in the space-time congruency effect, we asked participants to make lateralized eye movements (left or right saccades) to indicate whether stimuli were real words or not (lexical decision). Eye movement responses were slower and higher in amplitude for responses incompatible with the direction of the MTL. These results reinforce the claim that repeated directional reading and writing movements promote the embodiment of time-related words.